<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var username = prompt("请你输入用户名");
        var password = prompt("请你输入密码");
    do{
      alert("用户名或者密码有误")
    }
    while(username!="admin"||password!=123456)
    alert("登陆成功")
      
    </script>
</body>
</html>